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* [9fans] usb keyboard and mouse?
@ 2006-06-26 18:50 ISHWAR RATTAN
  2006-06-26 19:22 ` Francisco J Ballesteros
  2006-06-27  0:19 ` geoff
  0 siblings, 2 replies; 12+ messages in thread
From: ISHWAR RATTAN @ 2006-06-26 18:50 UTC (permalink / raw)
  To: 9fans


Got a machine that has usb ports only. Plan 9 iso gets
stuck (as no input can be provided form the kbd). Is there
a solution to this problem?

-ishwar



^ permalink raw reply	[flat|nested] 12+ messages in thread
* Re: [9fans] usb keyboard and mouse?
@ 2006-06-29  5:31 Mike Haertel
  2006-06-29  8:23 ` Charles Forsyth
  2006-06-29 11:55 ` Dan Cross
  0 siblings, 2 replies; 12+ messages in thread
From: Mike Haertel @ 2006-06-29  5:31 UTC (permalink / raw)
  To: 9fans

Er, no.  Legacy keyboard emulation is intended to work with any OS,
even if the OS bypasses the BIOS and directly fiddles with the PS/2
hardware.  It uses chipset magic to translate "in" and "out"
operations to ports 0x60 and 0x64 (the PS/2 keyboard ports) into
USB operations.

The implementation is chipset dependent.  Often what happens is
that the chipset recognizes an I/O request to port 0x60 or 0x64 and
aborts the request with an SMI (system management interrupt).  This
is a *very* non-maskable interrupt (more non-maskable than NMI...)
that causes the processor to save pretty much all its register state
in a special memory area, and jump to a handler in the system BIOS.
The BIOS SMI handler examines the saved register state, figures out
what the OS was trying to do, runs a software model of the PS/2
keyboard controller's state, chats with the USB keyboard, formulates
an appropriate response, emulates the I/O instruction the OS was
trying to do, and resumes execution of the OS at the instruction
following the I/O instruction.

Some chipsets might do it directly in hardware rather than using
the SMI+BIOS strategy.

>From: "Artem Letko" <aletko@gmail.com>
>To: "Fans of the OS Plan 9 from Bell Labs" <9fans@cse.psu.edu>
>
>but that's only if your kernel uses BIOS calls, right?
>
>On 6/26/06, geoff@collyer.net <geoff@collyer.net> wrote:
>> Some BIOSes have an option with a name like "enable legacy USB" or
>> "enable USB keyboard" that, if set, will simulate PS2 input from a USB
>> keyboard or mouse.


^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2006-06-29 23:50 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2006-06-26 18:50 [9fans] usb keyboard and mouse? ISHWAR RATTAN
2006-06-26 19:22 ` Francisco J Ballesteros
2006-06-27  0:19 ` geoff
2006-06-28 15:48   ` Artem Letko
2006-06-28 17:01     ` Francisco J Ballesteros
2006-06-28 23:02       ` C H Forsyth
2006-06-28 23:21         ` Ronald G Minnich
2006-06-29  5:31 Mike Haertel
2006-06-29  8:23 ` Charles Forsyth
2006-06-29 11:55 ` Dan Cross
2006-06-29 15:02   ` Ronald G Minnich
2006-06-29 23:50   ` Charles Forsyth

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